1. Field of the Invention
The present invention relates to a method of driving a liquid crystal display apparatus, and more particularly, to a method of generating a frame start pulse signal for instructing driving of a specific function of a source driver in a source driver chip of a liquid crystal display apparatus.
2. Description of the Related Art
In liquid crystal display (LCD) apparatuses, liquid crystals can transmit light by changing alignment of liquid crystal molecules according to input voltages, so that image data can be displayed.
Recently, among the LCD apparatuses, thin film transistor (TFT) LCD apparatuses have been widely and actively used, which are manufactured by using technologies of manufacturing silicon integrated circuits.
FIG. 1 is a view showing a panel driving system of a general liquid crystal display apparatus.
As shown in FIG. 1, the panel driving system of a liquid crystal display apparatus includes: a panel 30 which is constructed with liquid crystals, color filters, and the like; a gate driving unit 40 which is constructed with gate drivers 41, 42, and 43 for driving them; a source driving unit 20 which is constructed with source drivers 21, 22, and 23 for driving sources of the liquid crystal; and a timing controller 10 which controls the gate driving unit 40 and the source driving unit 20 and outputs pixel data.
Each pixel is constructed with a switch transistor and a liquid crystal device. A gate terminal of the switch transistor is driven by gate drivers 41, 42, 43 . . . . One terminal of the switch transistor except the gate terminal is connected to the liquid crystal device, and the opposite terminal is connected to an output terminal of one of source drivers 21, 22, 23 . . . .
A timing controller 10 controls the entire panel driving system of the liquid crystal display apparatus. The timing controller 10 transmits timing signals CLK, LOAD, and SPi for controlling the gate drivers and the source drivers and video signals R, G, and B to the source drivers 21, 22, 23, . . . .
In general, the timing controller 10 receives the video signals R, G, and B to be transmitted to the source drivers in a low voltage differential signal (LVDS) manner. The timing controller 10 transmits data to the source drivers in a mini low voltage differential signaling (mLVDS) manner.
In a conventional transistor-transistor-logic (TTL) manner used for the timing controller to transmit data to a driver integrated circuit (IC), there are problems of a low transmission rate, high current consumption, a poor electro-magnetic interface (EMI) characteristic. The LVDS manner is to greatly reduce a size of voltage swing of a signal by compensating for the problems of the TTL manner.
In addition, the mLVDS manner is to greatly reduce the current consumption and improve the EMI characteristic of the entire chip by further reducing the size of voltage swing. The data transmission in the LVDS and mLVDS manners are well known to the ordinarily skilled in the art of the liquid crystal display apparatus, and thus, detailed description thereof is omitted.
FIG. 2 is a timing diagram showing recognition of a reset signal in a liquid crystal display apparatus using a conventional mLVDS manner.
In a liquid crystal display apparatus using a conventional mLVDS manner, the reset signal is recognized by the following processes. Firstly, in a state that a load signal LOAD in a high state is input, a signal LV0+,− which are input data signals to be transmitted in the mLVDS manner is maintained in a low state for 200 ns or more (t2). After that, the signals are maintained in a high state for 3 CLKs or more (t3).
Next, the first low signal RST=L of the input data signal LV0+,− triggered at the rising edge of a clock signal CLK+,− is recognized as the reset signal. The timing controller transmits to a source driver a frame start pulse signal for instructing driving of a specific function of the source driver.
In the liquid crystal display apparatus using the conventional mLVDS manner, since the frame start pulse signal required for driving a specific function of the source driver is input from an external timing controller, there is a problem in that input pins for inputting of the frame start pulse signal into the source driver chip are additionally needed, and input lines for inputting the frame start pulse signal are additionally needed in a printed circuit board where the source drivers are mounted.